'Debridement' is a rather broad term, encompassing sucking up loose fronds of synovium (joint lining), meniscus or cruciate ligament and sucking out any joint debris. Arthroscopic debridement means that this is done using keyhole surgery, where a thin 'scope' is pushed into the joint (arthro=joint) to visualise the structures.
Arthroscopic debridement of the degenerative knee – Is there still a role? Law GW, Lee JK, Soong J, Lim JWS, Zhang KT, and Tan AHC. Asia Pac J Sports Med Arthrosc Rehabil Technol. 2019 Jan; 15: 23–28.
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